Effectiveness of contrast-associated acute kidney injury prevention methods; a systematic review and network meta-analysis

BACKGROUND

Different methods to prevent contrast-associated acute kidney injury (CA-AKI) have been proposed in recent years. We performed a mixed treatment comparison to evaluate and rank suggested interventions.

METHODS

A comprehensive Systematic review and a Bayesian network meta-analysis of randomised controlled trials was completed. Results were tabulated and graphically represented using a network diagram; forest plots and league tables were shown to rank treatments by the surface under the cumulative ranking curve (SUCRA). A stacked bar chart rankogram was generated. We performed main analysis with 200 RCTs and three analyses according to contrast media and high or normal baseline renal profile that includes 173, 112 & 60 RCTs respectively.

RESULTS

We have included 200 trials with 42,273 patients and 44 interventions. The primary outcome was CI-AKI, defined as ≥25% relative increase or ≥ 0.5 mg/dl increase from baseline creatinine one to 5 days post contrast exposure. The top ranked interventions through different analyses were Allopurinol, Prostaglandin E1 (PGE1) & Oxygen (0.9647, 0.7809 & 0.7527 in the main analysis). Comparatively, reference treatment intravenous hydration was ranked lower but better than Placebo (0.3124 VS 0.2694 in the main analysis).

CONCLUSION

Multiple CA-AKI preventive interventions have been tested in RCTs. This network evaluates data for all the explored options. The results suggest that some options (particularly allopurinol, PGE1 & Oxygen) deserve further evaluation in a larger well-designed RCTs.

Meta-Analysis of Individual Patient Data of Sodium Bicarbonate and Sodium Chloride for All-Cause Mortality After Coronary Angiography

We sought to examine the relation between sodium bicarbonate prophylaxis for contrast-associated nephropathy (CAN) and mortality. We conducted an individual patient data meta-analysis from multiple randomized controlled trials. We obtained individual patient data sets for 7 of 10 eligible trials (2,292 of 2,764 participants). For the remaining 3 trials, time-to-event data were imputed based on follow-up periods described in their original reports. We included all trials that compared periprocedural intravenous sodium bicarbonate to periprocedural intravenous sodium chloride in patients undergoing coronary angiography or other intra-arterial interventions. Included trials were determined by consensus according to predefined eligibility criteria. The primary outcome was all-cause mortality hazard, defined as time from randomization to death. In 10 trials with a total of 2,764 participants, sodium bicarbonate was associated with lower mortality hazard than sodium chloride at 1 year (hazard ratio 0.61, 95% confidence interval [CI] 0.41 to 0.89, p = 0.011). Although periprocedural sodium bicarbonate was associated with a reduction in the incidence of CAN (relative risk 0.75, 95% CI 0.62 to 0.91, p = 0.003), there exists a statistically significant interaction between the effect on mortality and the occurrence of CAN (hazard ratio 5.65, 95% CI 3.58 to 8.92, p <0.001) for up to 1-year mortality. Periprocedural intravenous sodium bicarbonate seems to be associated with a reduction in long-term mortality in patients undergoing coronary angiography or other intra-arterial interventions.

Does bicarbonate prevent contrast-induced nephropathy in cardiovascular patients undergoing contrast imaging?

A best evidence topic in cardiovascular surgery was written according to a structured protocol. The question addressed was whether administering sodium bicarbonate (NaHCO3) prevents contrast-induced nephropathy (CIN) in cardiovascular patients undergoing contrast imaging. In total, 266 papers were found using the reported search, 16 of which represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. CIN is thought to occur as a result of ischaemic or oxidative injury to the kidney. It is postulated that NaHCO3attenuates this renal damage by alkanizing renal tubular fluid thus reducing the generation of contrast-induced free radicals, which damage the kidney. Of the 16 trials, 15 recruited patients with various degrees of renal dysfunction at baseline. The benefit of using NaHCO3 was demonstrated at all stages of chronic kidney disease. Apart from four studies, 12 studies used low toxicity, low-osmolar contrast. Merten et al. published the first trial of NaHCO3 vs (saline) NaCl in preventing CIN, demonstrated a significantly lower rate in the NaHCO3 group and advocated its widespread use. Subsequent trials using the same regimen have collaborated these results. However, more recently, Gomes et al. concluded that NaHCO3 is not superior to saline-based hydration. Similarly, Brar et al. randomized 323 patients with moderate-to-severe renal insufficiency to receive either an NaHCO3 or an NaCl infusion and observed no difference in CIN rates. Two studies investigated the effects of rapid urine alkanization with bolus injections of NaHCO3 prior to contrast and found significant reductions in CIN rates compared with NaCl-treated groups. One study observed that NaCl is superior to NaHCO3, while all other studies showed a beneficial effect or no difference between NaCl- and NaHCO3-based hydration. The most recent meta-analysis by Jang et al. incorporated 3609 patients across 19 trials and concluded that NaHCO3-based hydration regimens are superior to NaCl-based ones. Based on this review, the authors recommend NaHCO3 alongside an NaCl hydration regimen. The exact regimen will depend on the context within which contrast is being administered and needs further evaluation.

Acute kidney injury

Acute kidney injury (formerly known as acute renal failure) is a syndrome characterised by the rapid loss of the kidney's excretory function and is typically diagnosed by the accumulation of end products of nitrogen metabolism (urea and creatinine) or decreased urine output, or both. It is the clinical manifestation of several disorders that affect the kidney acutely. Acute kidney injury is common in hospital patients and very common in critically ill patients. In these patients, it is most often secondary to extrarenal events. How such events cause acute kidney injury is controversial. No specific therapies have emerged that can attenuate acute kidney injury or expedite recovery; thus, treatment is supportive. New diagnostic techniques (eg, renal biomarkers) might help with early diagnosis. Patients are given renal replacement therapy if acute kidney injury is severe and biochemical or volume-related, or if uraemic-toxaemia-related complications are of concern. If patients survive their illness and do not have premorbid chronic kidney disease, they typically recover to dialysis independence. However, evidence suggests that patients who have had acute kidney injury are at increased risk of subsequent chronic kidney disease.

Preprocedural evaluation and endovascular treatment of iliofemoral artery disease without contrast media for patients with pre-existing renal insufficiency

BACKGROUND

Generally, both the preprocedural evaluation and endovascular therapy (EVT) for lower limb arteries require contrast media that is harmful for patients with chronic renal insufficiency. In the present study these procedures were performed without using nephrotoxic contrast media in patients with preexisting renal insufficiency and iliofemoral artery disease.

METHODS AND RESULTS

The 36 consecutive patients with chronic renal insufficiency underwent preprocedural evaluation with duplex examination, magnetic resonance angiography (MRA) without contrast media, and plain computed tomography (CT). A total of 51 lesions were treated using intravascular ultrasound (IVUS) without contrast media. The overall technical success was 100% without any complications. Pre- and postprocedural ankle-brachial indices changed from 0.59 ± 0.23 to 0.92 ± 0.14. The mean serum creatinine concentration before and after treatment, and 3 months after treatment did not change (2.1 ± 1.4, 2.0 ± 1.4, and 2.1 ± 1.6 mg/dl, respectively). The overall 3-month survival rate and limb salvage rate was 100%.

CONCLUSIONS

EVT comprising duplex, MRA, and CT for preprocedural evaluation and IVUS-guided procedure is feasible and may avoid intra-arterial contrast injection in selected patients deemed at high risk for renal failure from nephrotoxic contrast material.

Relationship between renal dysfunction and severity of coronary artery disease in Japanese patients

BACKGROUND

The relationship between renal dysfunction and the severity of coronary artery disease (CAD) was examined.

METHODS AND RESULTS

The severity of CAD in 572 patients was graded according to the number of stenotic coronary arteries, and the estimated glomerular filtration rate (eGFR) was monitored for 3 years. Patients were stratified into 3 eGFR groups: normal (>75 ml x min(-1) x 1.73 m(-2)), mild reduction (60-75) and chronic kidney disease (CKD: <60). There were 161 patients in the CKD group. The average number of stenotic coronary arteries was larger in the CKD group than in the other groups (normal vs mild reduction vs CKD =1.35+/-0.07 (SE) vs 1.22+/-0.08 vs 1.69+/-0.08 vessel disease (VD), P<0.001). During the 3-year follow-up, the renal function of 13.8% of the patients worsened. Those who showed more deterioration of eGFR had more severe CAD than those who did not (1.20+/-0.06 vs 1.61+/-0.06 VD, P<0.001). Multivariate analysis revealed that the severity of CAD was independently and significantly associated with the deterioration of eGFR.

CONCLUSIONS

Patients with CKD had more severe CAD, which may explain the high rate of cardiovascular events in these patients. Moreover, the prognosis of renal function was poor in patients with severe CAD, and CAD was found to be an independent risk factor for worsening of renal dysfunction.

Outcome definitions in non-dialysis intervention and prevention trials in acute kidney injury (AKI)

BACKGROUND

The risk, injury, failure, loss-of-function, end-stage-renal-failure (RIFLE) and acute kidney injury network (AKIN) consensus definitions of acute kidney injury (AKI) were established in part to facilitate comparison of trials. Contrast-induced nephropathy (CIN) has traditionally used a less demanding definition.

OBJECTIVES

To review use of RIFLE and AKIN as AKI trial outcome variables and contrast these with outcomes for CIN.

METHODS

We conducted a search of PubMed from 1 January 2005 to 31 December 2008 and 9 trial registries for randomized control trials for preventional or interventional treatment of AKI and CIN.

RESULTS

RIFLE or AKIN were outcome variables in 36% (n = 8) of the published (n = 22) and 18% (n = 4) of the current (n = 22) AKI trials. RIFLE was used to triage to intervention in three trials. The urine output definition of RIFLE and AKIN was an outcome in only two trials. In 18% (n = 8) of AKI trials, the CIN definition (increase in serum creatinine of > or =25% and/or > or =44 micromol/l) was the primary outcome. This was also the primary outcome in 56% (n = 13) of published (n = 12) and current (n = 11) CIN trials. Three published CIN trials used RIFLE or AKIN as an outcome (13%). The duration over which outcomes were determined varied from 24 h to 7 days.

CONCLUSIONS

Considerable heterogeneity remains in outcome variables of AKI and CIN clinical trials. Even when the RIFLE or AKIN criteria were used, they were not applied consistently. There is a need for further consensus on surrogate outcome variables.

Sodium bicarbonate for the prevention of contrast-induced nephropathy: a meta-analysis of 17 randomized trials

BACKGROUND

Contrast-induced nephropathy (CIN) is a common cause of acute kidney injury. Several preventive therapies for this injury have been tested; however, there is still no consensus on the optimal protocol.

METHODS

We performed a systematic search of the National Library of Medicine and the Cochrane Library databases from January 1985 to November 2008 to identify randomized controlled studies examining sodium bicarbonate as a preventive measure for CIN in humans. We also reviewed conference abstracts from cardiology nephrology and radiology meetings from 2004 to 2008. A change in serum creatinine levels defined by an absolute (>or=0.5 mg/dl) or percentage (>or=25%) increase in the serum creatinine level is defined as CIN. The primary outcome measure was the incidence of CIN, and the secondary outcome measures were: change in serum creatinine from baseline, requirement for renal replacement therapy and death.

RESULTS

Seventeen randomized controlled trials have investigated the role of sodium bicarbonate for prophylaxis of CIN. The overall incidence of CIN was 11.3%. Using the results from all 17 studies that compared bicarbonate versus saline, the pooled relative risk of developing CIN was 0.54 (95% CI, 0.36-0.83) in the intervention arm, indicating a significant benefit from sodium bicarbonate. The pooled relative risk of CIN was 0.57 (95% CI, 0.35-0.95) when we analyzed for the studies that compared the effects sodium bicarbonate to NAC on development of CIN. There was no difference in the rates of requirement for renal replacement therapy and death.

CONCLUSIONS

The use of sodium bicarbonate appears to reduce the incidence of CIN when compared to other preventive strategies for CIN without a significant difference in the requirement of renal replacement therapy and mortality. There are study heterogeneity and publication biases. Further adequately powered randomized controlled studies are needed to determine whether sodium bicarbonate will reduce the clinically meaningful outcomes (e.g., need for dialysis or death) and optimal hydration strategy in high-risk patients.

[Contrast induced nephropathy]

Contrast media induced nephropathy is a common complication, particularly in high risk patients, such as patients with chronic kidney disease (CKD) and diabetes. The majority of studies show an increased in-hospital mortality and an unfavourable long-term prognosis after manifestation of contrast media induced nephropathy. The course and the potential risk factors of this type of acute renal failure are known. Therefore, an effective prophylaxis should allow to prevent this complication. In low risk patients oral or intravenous volume expansion is probably sufficient combined with the withdrawal of non-steroidal anti-inflammatory drugs. In high risk patients additional prophylactic measures are needed but their efficacy is not clearly defined. Therefore, heterogeneous recommendations exist. Hydration reduces (afferent) renovasoconstriction, the tubuloglomerular feedback, the tubulotoxic effects of contrast media (via dilution) and the oxygen radical formation. The optimal composition, timing and amount of fluid which should be administered to the patients remain unclear. Most studies show that intravenous administration of volume is more effective than oral fluid intake. The majority of studies found a benefit of isotonic sodium bicarbonate in comparison to isotonic saline solutions, even if meta-analyses displayed only a positive trend for sodium bicarbionate due to the heterogeneity of the data. Controversies exist for N-acetylcysteine, vitamin C, fenoldopam, theophylline or statins. Due to low cost and low side effects, N-Acetylcysteine is widely used. Theophyllin (given intravenously 30 minutes before contrast media injection) is renoprotective, particularly in intensive care unit patients. Very important is the reduction of contrast media volume (if possible <30 ml for diagnostic procedures and <100 ml for interventions). Iso-osmolar and low-osmolar contrast media may have a comparable low risk for the induction of contrast media induced nephropathy. This risk is probably higher after intra-arterial as compared to intravenous administration of contrast media. Controversies exist with respect to the reduction of contrast media induced nephropathy and mortality by prophylactic hemodialysis or hemofiltration. A possible benefit of these procedures consists probably for patients with advanced chronic kidney disease (stage 5). With the further increase of investigations using contrast media, with the further increase in vascular interventions, in age and comorbidities of the patients one may suggest that the problem of contrast media induced nephropathy will further increase, despite all prophylactic procedures so far recommended.

Prevention of contrast media-induced nephropathy by isotonic sodium bicarbonate: a meta-analysis

BACKGROUND

The clinical value of hydration therapy using sodium bicarbonate in the prevention of contrast media-induced nephropathy is subject of controversy.

OBJECTIVE

This meta-analysis of randomized clinical trials was performed to determine whether hydration therapy using sodium bicarbonate consistently differs from control hydration regimens with normal saline in its preventive effects upon radiocontrast media-induced renal dysfunction.

METHODS

Randomized clinical trials comparing sodium bicarbonate with a control regimen for prevention of contrast media-induced nephropathy were selected by multiple methods, including computer searches of bibliographic databases, perusal of reference lists, and manual searching. Major findings were qualitatively summarized. In addition, a quantitative meta-analysis was performed on renal dysfunction data.

RESULTS

Altogether, 9 randomized clinical trials with a total of 2,043 patients were included. The pooled odds ratio was 0.45 (confidence interval, 0.26-0.79), indicating a significant treatment benefit of sodium bicarbonate compared to normal saline. Heterogeneity was detectable (p=0.016) and evidence of publication bias was present (p=0.012). After adjustment for presumed unpublished trials after trim-and-fill analysis, the estimated pooled odds ratio was 0.65 (confidence interval, 0.36-1.20).

CONCLUSION

This meta-analysis confirms that, based on currently available randomized trials, bicarbonate therapy is effective in preventing contrast media-induced nephropathy. However, study heterogeneity and publication bias are substantial, and therefore further controlled clinical trials are needed.